Variable frequency resonance tester without partial discharge for ultrahigh voltage transformer

Disclosed is a variable frequency resonance tester without partial discharge for an ultrahigh voltage transformer. A variable frequency power supply is accessed to a three-phase alternating current power supply, an output of the variable frequency power supply is connected to a low voltage end of an exciting transformer, a high voltage end of the exciting transformer is connected with a parallel compensation reactor, further, the parallel compensation reactor, a voltage divider and a low voltage end of a test object (namely an ultrahigh voltage transformer) are connected in parallel, a high voltage tail end of the exciting transformer, a tail end of the parallel compensation reactor, and a low voltage tail end, an iron core and a high voltage tail end of the test object are grounded, a low voltage head end and a high voltage head end of the test object and the tail end of the iron core are all connected to impedance testing input ends, impedance testing grounding ends are all grounded, and impedance testing output ends are all connected to a partial discharge tester. The variable frequency resonance tester has the system partial discharge interference smaller than 10pC without limitation of balance measurement and unbalance measurement.